US EPA

In March 2021, EPA released the Systematic Review Protocol for the Inorganic Mercury Salts IRIS Assessment (Preliminary Assessment Materials). As part of developing a draft IRIS assessment, EPA presents a methods document, referred to as the protocol, for conducting a chemical-specific systematic review of the available scientific literature. Protocols communicate the rationale for conducting the assessment of inorganic mercury salts, describe screening criteria to identify relevant literature, outline the approach for evaluating study quality, and describe the dose-response methods.

Mercury occurs naturally in geologic materials in the environment and can exist in inorganic form as salts. In its inorganic form, mercury occurs abundantly in the environment - primarily as the minerals (e.g., cinnabar (HgS), metacinnabar) - and as impurities in other minerals. Its geologic associations are with volcanic rocks and hydrothermal systems. The abundance of each of these in the environment make it available for combining with chlorine, sulfur, and other elements as it weathers to form these and other inorganic salts. Inorganic mercury salts can be transported in water and occur in soil.

Human exposure to inorganic mercury salts can occur both in occupational and environmental settings. Occupations with higher risk of exposure to mercury and its salts include mining, electrical equipment manufacturing, and chemical and metal processing in which mercury is used. In the general population, exposure to mercuric chloride can occur through the dermal route from the use of soaps and creams or topical antiseptics and disinfectants. Exposure may also occur from consuming outdated medicinal products, such as laxatives, worming medications, and teething powders.

This document presents a draft assessment plan for inorganic mercury salts that will be the subject of a peer review meeting in 2020 and that will define the scope and approach of the IRIS assessment for inorganic mercury salts.

The IRIS Program will use the methods for conducting the systematic review as described in the protocol to develop the draft assessment.

U.S. EPA. Systematic Review Protocol for the Inorganic Mercury Salts IRIS Assessment (Preliminary Assessment Materials). U.S. Environmental Protection Agency, Washington, DC, EPA/635/R-20/239, 2021.